Synthesis, Processing, and Characterization of Helical Polypeptide Rod-Coil Mixed Brushes.

Mixed polymer brushes of rod-type polypeptide and coil-type vinyl polymer brushes were synthesized via two sequential steps of vapor deposition surface-initiated ring-opening polymerization (SI-ROP) and surface-initiated atom transfer radical polymerization (SI-ATRP), respectively. The effect on polypeptide brushes by coil-type brushes of their surface morphology, film thickness, and orientation were investigated before and after solvent quenching processes using chloroform and acetone. Before solvent quenching, the as-grown coil-type brushes forced the polypeptide brushes to stand up from the surface, resulting in higher film thickness, but the polypeptide brushes remained randomly oriented. After solvent quenching, polypeptide brushes tended to aggregate into conical bundles with an orientation perpendicular to the substrate, but coil-type brushes restricted the free arrangement of the polypeptide brushes and lessen their upward movement. Changes in film thickness, rod orientation, morphology, and wettability were observed with increased molecular weight of the coil-type polymer in the mixed brushes.